Not sure what the above guy is talking about. I came up across this page also while wondering what laptop PC3-8500F was.

However, it's definitely not FB-DIMM. FB-DIMMs were only made for DDR2 on Intel dual 771 chipsets (5000, 5100, 5400). Once you've see how hot those things run (hot enough to fry bacon on), you'd know they'd never be in a laptop.